As an engineer, I was already aware of the concept of infinity, and accepted not only its possibility, but reality. As an engineer, I was also aware of an order in the Universe that could not come from anything else but a Rational Consciousness directing it. From there, it was a small step to realize that this Rational Consciousness, because It took the time to direct the Universe, was interested in me. I realized I had a Creator, and He was concerned about His Creation.
If this Creator was concerned about me, is it not rational to assume that He would take the time to make Himself known to me? This was the crux of my belief, and it was obtained not from reading Scripture (remember, at this time, I was shaken in my Christian faith), but merely from observing with the mental gifts I had (that I accepted came from my Creator) as an engineer.
Along this tortured path, I recalled that in Scripture, it stated that God had revealed Himself to all His creation, even before a single word of Scripture was written down. This is what is called Natural or General Revelation by theologians. This made sense, even in my doubtful frame of mind. IF THERE WERE SIMILARITIES BETWEEN MY FAITH AND ALL THE OTHER RELIGIONS AROUND IT, AND THAT EVEN PREDATED IT, THEN IT WAS ONLY BECAUSE GOD HAD REVEALED HIMSELF TO EVERYONE ON EARTH ALREADY A VERY LONG TIME AGO.
The next step in my mental spiritual struggle was in figuring out why there were different religions, if there was only one revelation and one Revelator from the beginning. I started reading the Church Fathers, and boy did they help me out. The earliest Church Fathers testified that religions were different because either man sought to add to the pure revelation, or because the Devil, under various guises, came to mislead man. In fact, these Fathers were wont to identify the many different gods of the various religions as demons – fallen angels – in disguise.
So does the pure revelation of the one Revelator still exist, and if it does, where can I find it?
To make a long story short, the search led me to the Catholic Church.
I hope this has helped you out. If you have any questions, please, please, please feel free to ask.
P.S. May I suggest you subscribe to This Rock magazine. It has a great section in every issue called “Damascus Road” which features conversion stories (actually, it is the best section, in my opinion). They are moving and will give you some of the in-depth reasons that people have for joining the Church. The thing I find especially relevant about these conversion stories is that none of them are based on a bad experience of their former faith or position (e.g., bad pastor, bad parishioner, bad music, boring liturgy, etc). So there is a real sense that these conversions are genuine, instead of merely a stop along a long emotional road.
P.P.S. As your concern right now is different from when we first corresponded, do you still want that biblical and patristic proof for the principle of invincible ignorance. That topic seems more in the plane of high-level apologetics, than the basic soul-searching with which we are concerned at the moment.